If you have any difficulty in opening a case under eBay's money back guarantee you may need to contace customer support for help. It can be problematical if the seller has been removed from eBay.
As has been said,it won't be the seller who has closed their account. eBay doesn't allow sellers to close accounts whilst the time limit for refund claims remains open.
Personally, I wouldn't even waste time trying to contact a seller who has been expelled. They may try to string you along with promises until eBay's 30 day time limit has closed. It happens all the time.
How did you pay? If any problems it may be better to see whether your payment provider (e.g. credit or debit card) can help.